Aqueous coating agent and aqueous emulsion, process for the preparation thereof

ABSTRACT

An aqueous coating agent on the basis of one or more polyols having ionic groups or groups convertible into ionic groups, which can contain pigments, fillers and/or optional conventional lacquer adjuvants and/or solvents, comprising 
     A) 10 to 40 wt.-% of one or more polyols having a number-average molecular weight (Mn) of 500 to 200000, an OH-number of 15 to 300 and a content of ionic groups and/or groups convertible into ionic groups of 5 to 400 meq/100 g solid resin, which are at least partly neutralized, 
     B) 0.5 to 10 wt.-% of one or more chlorinated polyolefines having a chlorine content of 15 to 35 wt.-%, 
     C) 5 to 40 wt.-% of one or more aromatic solvents having a boiling range from 100° to 160° C., 
     D) 25 to 75 wt.-% of water, 
     E) 0 to 30 wt.-% of one or more further water dilutable binders which are free from groups reactive with NCO, 
     the percentages by weight of components A) to E) adding up to 100 wt.-% and 
     F) one or more polyisocyanates having on average at least two free isocyanate groups per molecule, in such an amount that the ratio of the number of reactive isocyanate groups to the OH-groups of the polyols is 0.5:1 to 5:1, 
     the coating agent being a two-component system, one component containing the polyols and the other component containing the polyisocyanates.

The invention refers to aqueous coating agents on the basis of polyolswhich can be crosslinked with polyisocyanates and which containchlorinated polyolefines as adhesion mediators. The invention relatesalso to the preparation of the aqueous coating agents from the aqueousemulsions containing chlorinated polyolefines; it refers also to the useof the coating agents especially for coating plastic materials.

Aqueous two-component systems on the basis of epoxide resins and aminoresins have been described in DE-A-41 23 860. This reference refers tospecific dispersions from epoxide resins, amino resins and polyurethaneswhich are used together with pigments and adjuvants for the preparationof primers for the automotive industry. EP-A-0 358 979 describes aqueoustwo-component coating agents consisting of an acrylate component and apolyisocyanate component. Such coating agents can be used for metalsubstrates; however, if they are used for coating plastic materials,especially polyolefines, the adhesion to the substrate is notsufficient. This is demonstrated by a low resistance against water ofthe coated substrates. Further it is not possible to prepare thicklayers with such coating agents. Preparing thicker layers furnishesdefects such as small blisters and pin holes. DE-A-39 10 901 and thecorresponding WO 90/12056 describe coating compositions for plasticmaterials containing water, a film-forming binder system, chlorinatedpolyolefines (CPO), as well as optional pigments and adjuvants. Thefilm-forming binders are acrylate resins or polyurethane resins in anaqueous emulsion. After application of such coating agents the systemsdry physically. For the preparation of such coating agents it isnecessary to use specific emulsifiers as well as a melt process for thechlorinated polyolefines; further it is necessary to carry out anazeotropic destillation of all organic solvent components. This is verycostly.

DE-A-41 31 127 describes adhesion primers on the basis of chlorinatedpolyolefines, organic solvents, water, emulsifiers as well as pigmentsand an optional film-forming binder which can be used for coatingplastic materials. The systems dry physically, i.e. no chemical reactionoccurs in the coated film. If such primer layers are coated with coatingagents containing organic solvents, the risk of re-dissolving of theprimer layer has to be taken into consideration. Otherwise defects ofthe coated surfaces can occur.

EP-A-0 466 136 describes specific aqueous coating agents for coatingplastic substrates, containing a combination of olefine resins, urethaneresins and epoxide resins. An example for an olefine is chlorinatedpolypropylene.

It is the object of the present invention to provide aqueous coatingagents which can be used for coating plastic moldings, especially in theautomotive industry and which furnish coatings having a good impactresistance even when cold, having a smooth surface free of defects evenif thick layers are applied.

It has been found that this object can be achieved by an aqueous coatingagent on the basis of one or more polyols having ionic groups or groupsconvertible into ionic groups, which can contain pigments, fillersand/or conventional lacquer adjuvants, comprising:

A) 10 to 40 wt.-% of one or more polyols having a number averagemolecular weight (Mn) of 500 to 200000, an OH-number of 15 to 300 and acontent of ionic groups and/or groups convertible into ionic groups of 5to 400 meq/100 g solid resin, which are at least partly neutralized, theionic groups being preferably anionic groups,

B) 0.5 to 10 wt.-% of one of more chlorinated polyolefines having achlorine content of 15 to 35 wt.-%,

C) 5 to 40 wt.-% of one or more organic solvents having a boiling rangefrom 100° to 160° C.,

D) 25 to 75 wt.-% of water,

E) 0 to 30 wt.-% of one or more further water dilutable binders whichare free from groups reactive with NCO,

the percentages by weight of components A) to E) adding up to 100 wt.-%and

F) one or more polyisocyanates having on average at least two freeisocyanate groups per molecule, in such an amount that the ratio of thenumber of reactive isocyanate groups to the OH-groups of the polyols is0.5:1 to 5:1,

the coating agent being a two-component system, one component containingthe polyols and the other component containing the polyisocyanates.

It has been found that the coating agents of the invention can beprepared from aqueous emulsions of one or more chlorinated polyolefineshaving a chlorination degree of 15 to 35 wt.-%. They can be preparedessentially or totally free from emulsifiers if they are dispergedtogether with polyols; the polyols are such which can be used in theaqueous coating agents of the invention. However, it is also possible toprepare the coating agents of the present invention in any other way.For example, the chlorinated polyolefines can be used together with anemulsifier.

The coating agents of the present invention are especially two-componentsystems, one component containing the polyols and the other containingthe polyisocyanates. The polyol component is diluted with water; thepolyiscocyanate component can be disperged together with the polyolcomponent in water. The chlorinated polyolefines, as well as theoptional pigments, fillers and conventional lacquer adjuvants can becontained in one or both components. It is clear that any substanceswhich are dispersed in the polyol component A) should be compatible withwater in order to achieve a good storage stability. Additives which areused with the polyisocyanate-crosslink component should not be reactivewith the polyisocyanates. Generally it is convenient to disperseorganophilic substances in the polyisocyanate component.

The polyol component A) which can be used in accordance with the presentinvention is especially based on binders on the basis of radicallypolymerisable monomers containing OH-groups, OH-group containingpolyesters and/or OH-group containing polyurethanes. The number-averagemolecular weight is 500 to 200,000, the OH-number is 15 to 300 mg KOH/gsolid resin. The dispersability in water is achieved by polar groups,e.g. OH-groups, ether groups, urethane groups, ionic groups or groupswhich are convertible into ionic groups. It is possible to use kationicgroups or groups which are convertible into kationic groups, e.g. aminogroups; however, anionic groups or substituents convertible into anionicgroups, e.g. carboxyl groups, phosphoric acid groups and sulfonic acidgroups are especially convenient. Polymers having carboxyl groups arepreferred. The content of ionic groups is 5-400 meq/100 g solid resin.The polyol component is provided in the form of an aqueous dispersionhaving a viscosity of 100-10000 mPas at 23° C. The pH is 5-10.

Examples for suitable COOH- and OH-groups containing polymers on thebasis of olefinically unsaturated monomers are described inEP-A-0358979. These are aqueous dispersions on the basis of olefinicallyunsaturated monomers. Such monomers can be free from functional groups,examples are styrene, (meth)acrylic acid alkylesters having C₁ -C₈ inthe side chain, vinyl acetate or (meth)acrylonitrile. Further, at leastparts of the monomers can have functional groups, e.g. hydroxyl groups,such as hydroxyalkyl ester of (meth)acrylic acid, for example2-hydroxyethyl acrylate or 2-hydroxypropyl acrylate. Further it ispossible to insert other reactive groups, e.g. epoxide groups or amidogroups, using monomers such as, e.g. glycidyl(meth)acrylate orN-methoxymethyl(meth)acrylamide. The ionic groups can be inserted usingolefinically unsaturated monomers, containing functional groups whichcan be converted into ionic groups, e.g. olefinically unsaturated mono-or dicarboxylic acids having a molecular weight of 72-207, such as, e.g.acrylic acid, maleic acid, itaconic acid and the halfesters thereof orusing compounds such as 2-acrylamide-2-methylpropane-sulfonic acid.

The preparation of the polymerisates is carried out in accordance withusual processes, e.g. as polymerisation in solution. It is possible touse continuous and discontinuous processes. The copolymerisation isgenerally carried out using initiators and optional regulating compoundsat temperatures of 50° to 160° C. It is carried out in a liquid whereinmonomers or polymers are both soluble. Preferred solvents are organicsolvents which are not detremental to the coating agents to beformulated. The solvents are preferable organic solvents which are atleast partly miscible with water. Generally the initiators are used inamounts of 0.1 to 3 wt.-%, relating to the amount of monomers; examplesare peroxides and/or azocompounds and/or peresters. Specific examplesare benzoyl peroxide, cumol hydroperoxide, tert.-butyl peroctoate or2.2-azobis(2-cyanopropane).

It is possible to reduce the molecular weight by the use of regulatingcompounds. Preferred regulating compounds are mercaptanes, halogenecontaining compounds or other substances transferring radicals. Specificexamples are n-dodecyl mercaptane, butan-1-ol or dimeric α-methylstyrene.

Examples for solvents for the polymerisation are aromatic solvents suchas toluene, xylene; esters, such as ethyl acetate, butyl acetate, ethylglycol acetate; ethers such as butylglycol or ethylglycol ether; ketonessuch as acetone or methylethyl ketone. If desired the solvents can beremoved by destillation, preferably in vacuum from the polymerisatesbefore or after dilution with water.

The number average molecular weight (Mn) of the binders on the basis ofradically polimerisable monomers is preferably 500 to 50,000,particularly preferred from 1000 to 10,000. The OH-number is 15-300,preferably 30-170 mg KOH/g solid resin. The content of polar, e.g.anionic, groups is 5-400 meq, preferably 25 to 280 meq per 100 g solidresin.

Examples for acidic water dispersable polyurethane resins are describedin DE-A-41 24 453 and DE-A-40 00 889. Examples are polyurethane resinsprepared by the reaction of two valent or multivalent saturated linearor branched aliphatic or cycloaliphatic polyalcohols with linear orbranched aliphatic, cycloaliphatic or aromatic polyisocyanates, e.g.diisocyanates, and optional linear or branched aliphatic orcycloaliphatic monoalcohols. In order to insert ionic groups, it is,e.g. possible, to insert by reaction low molecular dialcohols having ananionic group or a group convertible into an anionic group, preferably acarboxyl group.

The reaction is carried out at temperatures from 20° to 150° C.,optionally using catalysts. The reaction can be carried out by meltingor in solution in inert dry solvents. A stepwise reaction is alsopossible. Linear or branched molecules are formed in accordance with theamount of multivalent polyols. If an a excess of alcohols is used,terminal hydroxy groups are formed at the end of the chains.

The polyols based on polyurethanes have preferably an OH-number of 20 to200. The acid number is preferably 10 to 200, especially preferred 25 to150. The number average molecular weight (Mn) is preferably 3000 to200,000. In accordance with a preferred embodiment the water dispersablepolyurethane resins for component A) have an number-average molecularweight of 3000 to 50,000, an OH-number of 30 to 150 and an acid numberof 25 to 70. Particularly preferred are carboxyl groups as groupsconvertible into anionic groups.

Examples for polyols which can be used in accordance with the presentinvention are hydroxy groups containing polyesters having anionic groupsas described in DE-A-32 13 160, DE-A-28 24 418 and U.S. Pat. No.3,053,783. In accordance with the present invention it is possible touse linear or branched oil-free polyesters on the basis of two valent ormulti-valent linear or branched aliphatic or cycloaliphatic saturatedpolyalcohols and linear or branched aliphatic, cycloaliphatic oraromatic two valent or multi-valent carboxylic acids which can bepolycondensed with linear or branched aliphatic monoalcohols.

Preferably the alcohols contain 2 to 21 C-atoms; the two valent ormulti-valent carboxylic acids contain preferably 5 to 10 C-atoms.Examples for polyalcohols are diols, such 2.6-hexanediol,neopentilglycol, 2.2.4-trimethylpentanediol-1.3 or1.4-bis-(hydroxymethl)cyclohexane. Examples for dicarboxylic acids areisophthalic acid, terephthalic acid, 1.3-cyclohexanedicarboxylic acid orbutylisophthalic acid. It is also possible to use small amount oftricarboxylic acids or trialcohols or polyalcohols in order to achievebranched structures. It is, e.g., possible to insert anionic groupsadditionally by reaction with a low molecular dialcohol containing anacid group which can be transformed into an anion, e.g. sulfonic acidgroups, phosphoric acid groups or carboxyl groups. Particularlypreferred are carboxyl groups, which, e.g., can be inserted by the useof dimethylolpropionic acid.

It is also possible to enhance the molecular weight of the polyesters byreaction with diisocyanates. Further, it is possible to modify them viareactive groups, e.g. OH-groups.

The polyesters which can be used in accordance with the presentinvention have preferably a number-average molecular weight (Mn) from1500-15000, particularly preferred from 2000-6000. The OH-number ispreferably 20 to 200, particularly preferred 40 to 150. The acid numberis preferably 20 to 150.

The preparation of the polyesters can be carried out in accordance withknown processes. It is preferred to work stepwise. They can, e.g., beprepared azeotropic or in a melt. The reaction temperature is, e.g.,150° to 240° C. After achieving of the desired parameters, it isoptionally possible to dilute the polyester with solvents in order toachieve a good working viscosity.

The qualities of the polyesters can be influenced by the useddicarboxylic acids or polyalcohols. Thus, long chain aliphatic alcoholsenhance the flexibility of the polyesters; aromatic dicarboxylic acidsreduce the elasticity. The branching degree can be influenced by theamount of used tricarboxylic acids. The water dispersability of thebinders is influenced by the amount of polar groups, e.g. OH-groups,ether groups, urethane groups or ionic groups.

The polyols A) which can be used as binders in accordance with theinvention, can be transformed into the aqueous phase afterneutralisation of at least a part of the present ionic groups, withoutaddition of emulsifiers. The obtained aqueous systems can be realsolutions, colloid disperse systems or dispersions. It is possible thatthey still contain small amounts of organic solvents from theirpreparation; however, such organic solvents can also be added in orderto improve specific qualities such as flow or dispersability. It ispossible to assist the transformation into the aqueous phase by, e.g.,enhancing the temperature. However, it is also possible to remove theorganic solvents by destillation from the aqueous dispersion.

The crosslinking component F) used in accordance with the inventioncontains polyisocyanates which, on average, contain at least two freeisocyanate groups per molecule. Examples for such polyisocyanates aredescribed in EP-A-0 358 979. They are organic polyisocyanates, e.g.diisocyanates, with aliphatic, cycloaliphatic and/or aromatic bound freeisocyanate groups, which are liquid at room temperature, which can alsobe achieved by the addition of solvents.

The ready polyisocyanate component has a viscosity of 50-10,000,preferably 50-1000 mPas at 23° C. If necessary, it is possible to mixdifferent polyisocyanates. Further, it is also possible to add inertsolvents in order to reduce the viscosity to a desired degree. In orderto achieve this it is preferred to use solvents which are partly mixablewith water.

Examples of usable polyisocyanates are the known conventional lacquerpolyisocyanates such as, e.g., hexamethylene diisocyanate (HDI),isophorone diisocyanate (IPDI), toluylene diisocyanate (TDI) andtetramethyl xylylene diisocyanate (TMXDI). Such diisocyanates can betransformed by known processes into oligomers, which, e.g. containbiuret groups, urethane groups, uretdione groups or isocyanurate groups.It is also possible to react them with lower alcohols, e.g.trimethylolpropane. Polyisocyanates containing biuret groups on thebasis of HDI as well as the corresponding cyclic trimerisates of HDI arepreferred. The use of oligomers on the basis of TMXDI is also preferred.The isocyanates can be used as such or in the form of mixtures. Theaverage functionality is 2 or more.

The chlorinated polyolefines (CPO) which can be used as component B) inaccordance with the invention, are commercial products. They are, e.g.,chlorinated polyethylene, chlorinated polypropylene or chlorinatedpolyethylene/polypropylene copolymers or mixtures thereof. Thechlorinated polyolefines have a chlorination degree (a chlorine content)of 15-45 wt.-%. Generally they are dissolved in organic solvents.However, it is also possible to use them in the form of an aqueousdispersion.

A further object of the present invention are aqueous emulsions ofchlorinated polyolefines, which, e.g., can be prepared from asolvent-containing form of the chlorinated polyolefine B) together withthe water dilutable polyol component A) (totally or partial) andoptional water and/or aromatic solvents. In this case the polyolcomponent A) can be in the form of a binder and can be disperged withthe further components with water, or it is possible to use an aqueousdispersion of the polyol. This can be achieved by mixing the componentswith known disperging apparatus; if desired it is possible to prepare apre-emulsion which can further be treated with disperging apparatus,e.g. rotor-stator-mixers, impellers, such as propellers, ultrasonicmixers or high-pressure homogenisators. Working in this way it ispossible to omit emulsifiers. It is also possible to start withCPO-powders without solvents and to add the necessary amounts ofaromatic solvents together with the water.

Examples for solvents are organic solvents having a boiling range of100° to 160° C., especially aromatic solvents, such as toluene, xyleneor mixtures thereof.

Preferably the emulsions of the present invention have a content of 10to 100 wt.-% of one or more aromatic solvents having a boiling rangefrom 100° to 160° C., as exemplified above. The amount of CPO is, e.g.,5 to 70 wt.-%, relating in each case to the polyol component. Theemulsions of the present invention are storage-stable products; no phaseseparation occurs. It is possible to use them directly for thepreparation of the coating agents of the invention, e.g. by directaddition to the coating agents or to one or both components thereof.

The emulsion prepared in accordance with the invention can be useddirectly for the preparation of the coating agents of the invention.However, it is also possible to use other dispersions of chlorinatedpolyolefines in the coating agents. Examples for usable dispersions ofchlorinated polyolefines (CPO) are described in DE-A-41 31 127. They areaqueous CPO-dispersions containing aromatic solvents and an anionicemulsifier. Examples for the aromatic solvents are specified above. Thecontent of aromatic solvents is, e.g., 15 to 50 wt.-%. The describedaqueous solvent containing CPO-dispersions are prepared by dispergingthe CPO in the form of a powder, slurry or an organic solution using anemulsifier in water at an elevated temperature.

During the preparation of the polyol-containing emulsion of the presentinvention as well as during the preparation of the described emulsionwhich is free from binders, it is possible to start with the preparationof a pre-emulsion which is optionally added with water, further organicsolvents or adjuvants in order to achieve a suitable solids content andwhich is further homogenized. The obtained dispersions have a gooddistribution of the particle size in the aqueous phase. It is possibleto directly add the dispersions to the coating agent or to one or bothcomponents thereof.

It is possible that the coating agents of the invention containadditional water dilutable binders E) which essentially do not containany groups which can be crosslinked with the isocyanates under curingconditions, e.g. water dilutable polyurethane resins or acrylate resinsor polyester resins. They are preferably aqueous polymer dispersionswhich are admixed to the polyol of component A). The maximum amount ofsuch binders is 75 wt.-% relating to the reactive film-forming polyol.

Further, the coating agents of the invention can contain conventionallacquer additives such as defoaming agents, wetting agents, thickeningagents, anti cratering agents, flowing agents, light protective agentsor catalysts. The added substances shall be compatible with thecomponent to be admixed or they shall form a storage-stable form. If thenecessary amount of solvents cannot be inserted by the CPO-emulsion orby the binders it is also possible to add further organic solvents tothe coating agents. They can be conventional lacquer solvents,especially aromatic solvents which are known to the person skilled inthe art. The total amount is 5 to 40 wt.-%.

The coating agents of the invention can also contain organic and/orinorganic pigments or fillers. Examples are organic and inorganiccoloured pigments, effect pigments such as metallic pigments, mica,alluminium silicate, titanium dioxide, barium sulfate, high dispersesilica and corrosion protective pigments. It is also possible to addcrosslinked organic polymer particles as fillers. The pigments and/orfillers have a preferred particle size of 15 μm and less. This can beachieved by grinding the pigments in auxiliary substances, e.g. pasteresins or wetting resins. The processes for disperging pigments aredescribed in the literature and are known to the person skilled in theart.

In order to prepare the coating agents, the film-forming resins aretransformed in the aqueous phase. They can be totally or partiallyneutralized before or after transformation into the aqueous phase, inorder to achieve a stable aqueous emulsion. The solvent-containingCPO-composition is contained in the binder component as an aqueoussolvent containing a dispersion or as an emulsified organic solution;further non-reactive aqueous binders can also be contained. Thiscomponent can contain optional adjuvants or pigments and fillers. If thepigments are directly disperged into the aqueous binder composition, itis necessary to take into consideration that the stability of thedispersion is not impaired by the binding process. On the other hand, itis also possible to add ground aqueous pigment compositions, e.g.so-called pigment pastes, to the dispersion of binders.

The coating agents of the invention are two-component systems(2K-systems).

The second component contains the polyisocyanate F). Other adjuvants,e.g. defoaming agents, to achieve good lacquer effects, as well aspigments, can also be contained in this component. It is also possibleto insert into this component at least a part of the CPO. Only suchcomponents should be added to the polyisocyanates which are not reactivewith the isocyanate groups. It is possible to adjust the viscosity ofthis component by the addition of inert solvents.

The coating agent is obtained ready for use by dispersing thepolyisocyanate component into the aqueous dispersion of the bindercomponent. The amounts are chosen in such a way that the ratio of theamount of reactive NCO-groups to the amount of OH-groups is 0.5:1 to5:1, preferably 0.8:1 to 2:1. It is necessary to mix those componentswell.

A preferred embodiment of the coating agents of the invention comprises

    ______________________________________                                        10-40 wt. % of binder and crosslinking agent                                  0.5-7 wt. % of CPO                                                            5-30 wt. % of aromatic solvents                                               0-25 wt. % of pigments and/or fillers                                         0-15 wt. % of further binders and                                             25-75 wt. % of water.                                                         ______________________________________                                    

Depending on the kind of application the coating agent can be adjustedwith water to a desired viscosity. The kind and amount of pigments andfillers are chosen in accordance with the desired use. For primercoatings the pigment content is high. For the use as a top coat thepigment content is mostly within the lower range of amounts and thepigments are coloured or effect pigments. Clear coats do not containpigments, however transparent colouring agents can be used.

The coating agents of the invention can be used on substrates such asmetals and plastic materials. Plastic substrates are especiallypreferred. Examples are modified or non-modified polyolefines,especially polyethylene or polypropylene, polycarbonate, polyamide,ABS-polymers, polyurethanes or polyesters. Polyolefine substrates arepreferred. It is possible to use known processes for the application ofthe coating agents, such as painting, rolling, spraying or dipping. Thecoating agents can be applied directly to the purified substrate; it isnot necessary to use an adhesive primer. Preferably the thickness of thelayers is 5-75 μm. However, surprisingly it has been found that evenwith thick layers a smooth surface without blisters or pinholds isachieved.

Crosslinking of the coating agents is achieved at temperatures of, e.g.10° to 120° C., preferably 40° to 100° C. The crosslinking speed can beinfluenced by addition of usual catalysts. If desired it is possible toinsert an aeration phase at low temperatures after application beforecrosslinking by heating. The crosslinking temperature can be chosen inaccordance with the temperature sensibility of the substrate.

Homogenously coated substrates are achieved after crosslinking, e.g.plastic substrates having a good adhesion between film and substrate.The surface is smooth and free from defects even when preparing thicklayers. Also the adhesion to further coating layers is good. It ispossible to achieve thick layers without defects of the surface of thefilms by blisters or sagging. The mechanical qualities of the coatedmaterial, e.g. the impact resistance is not impaired, even when cold.The coating agents are especially useful for the preparation ofbase-coat layers in multi-layer systems. It is possible to apply one ormore further coatings, e.g. transparent coatings, stonechip-resistantcoatings or base coats/top coats to the thus obtained coatings. Theachieved multi-layer coating shall have a good adhesion at the substrateand a good elasticity even when cold. They can be used withoutadditional adhesion primer. A further preferred embodiment comprises theuse as a one-component top coat. The coating agents of the invention areespecially useful for coating plastic pieces in the automotive industryor the industry furnishing the automotive industry. However, they canalso be used for coating of other substrates, especially temperaturesensitive plastic.

The following examples explain the invention. Percentages relate to theweight unless stated otherwise.

EXAMPLE 1

29 wt.-% of a 25% solution of a chlorinated polypropylene having achlorine content of 18% in xylene are added to 66% of a 26.5% dispersionof an acrylate resin (in accordance with example G of EP-A-0 358 979)and 5% water. The mixture is homogenized thoroughly using a propeller at9000 rpm at 23° C. and using an eccentric geometry of agitation. It hasto be ensured that no unagitated zones remain in the material to bedisperged. The CPO-solution is added slowly. (Solids content ca. 25%).

EXAMPLE 2

50 wt.-% of an aqueous polyurethane dispersion (in accordance withDE-OS-40 00 889 solids content 35%) are added with 14% water and slowlymixed with 26% of a 25% solution of a chlorinated polypropylene having achlorine content of 18% in xylene. The mixture is thoroughly homogenizedwith a propeller at ca. 9000 rpm at 23° C. using an eccentric geometryof agitation. The existence of unagitated zones in the material to bedispersed is to be avoided (solids content ca. 24%). The obtainedaqueous solvent containing emulsions are storage-stable and they can beused for the preparation of coating agents.

PREPARATION EXAMPLE 3

34.5% of an aqueous acrylate resin (in accordance with example F) ofEP-A-0 358 979, solids content ca. 28%) are mixed with 4.0%demineralized water and a premixture of 0.15% of a commercial acrylatethickener (Acrysol RM 8) and with 0.95% water. 0.15% of a commercialionic emulsifier and 0.15% of a defoaming agent are added andhomogenized. 17.4% titanium dioxide, 3.8% talc and 0.05% carbon blackare added successively into this mixture. The viscosity is adjusted withca. 1.75% water and the mixture is grounded on a bead mill for 30minutes.

This mixture is added slowly with a stable emulsion (in accordance withDE-A-41 31 127) from 9.65% of a commercial CPO (solids content 25% inxylene), 0.65% of an emulsifier on the basis of alkyl sulfonate and 9.0%demineralized water. A storage-stable aqueous CPO/xylene containingcomponent is obtained.

PREPARATION EXAMPLE 4

32.35% of an aqueous acrylate resin (in accordance with example F) ofEP-A-0 358 979, solid content ca. 28%) are mixed with 3.9% demineralizedwater and a premixture of 0.15% of a commercial acrylate thickener with0.95% water. 0.15% of a commercial emulsifier and 0.15% of a defoamingagent are added and homogenized. 16.3% titanium dioxide, 3.6% talc and0.05% carbon black are successively disperged into this mixture. Theviscosity is adjusted with ca. 1.6% water and the mixture is ground in abead mill for 30 minutes.

A stable emulsion of 15.1% of a commercial CPO (solids content 25%xylene), 1.0% of an emulsifier on the basis of alkylsulfonate and 14.1%demineralized water is slowly added to this mixture. A storage-stableaqueous CPO/xylene-containing component is achieved.

PREPARATION EXAMPLE 5

55.0% of an emulsion according to example 1 are mixed with a premixtureof 0.15% of a commercial acrylate thickener with 0.95% water. 0.1% of acommercial ionic emulsifier, 0.2% of a defoaming agent and 1.8% waterare added and homogenized. 17.0% titanium dioxide, 3.8% talc and 0.05%carbon black are successively disperged into this mixture. The viscosityis adjusted with ca. 1.5% water and the mixture is ground in a bead millfor 30 minutes.

EXAMPLE 6

82.2% of the component of example 3 are mixed with 11.2% of a solutionof 4.65% of a mixture of aliphatic hydrocarbons and 6.65% of a mixtureof oligomer biuret and isocyanurate-group containing HDI-condensationproducts having a NCO-content of 22%; the resultant mixture ishomogenously agitated. An application viscosity is achieved by adjustingwith 6.6% water.

EXAMPLE 7

89.4% of the component according to example 4 are mixed with 9.3% of asolution of 3.0% of a mixture of aliphatic hydrocarbons and 6.3% of amixture of oligomeric biuret and isocyanurate group containingHDI-condensation products having a NCO-content of 22% and the mixture ishomogenously stirred. 1.3% solvent are admixed in order to adjustapplication viscosity.

EXAMPLE 8

80.4% of the component of example 5 are added with 5.9% of a mixture ofoligomeric biuret and isocyanurate group containing HDI-condensationproducts having a NCO-content of 22%; the obtained mixture ishomogenously stirred. 13.65% water are added in order to adjustapplication viscosity.

Adhesion primer tests

The resultant primer coatings are sprayed onto a plastic substrate(Hostalen PPX 653 of Hoechst AG) which had been degreased, in order toachieve a dry film thickness of ca. 25 μm. The film is aerated for 15minutes and then dried for 15 minutes at 80° C. Then a furtherconventional coating system is applied.

Multilayer system:

25 μm 2K-primer according to examples 6 to 8

15 μm commerical water base coat (Diamantsilber 65 120 of Herberts GmbH)

35 μm commercial two-component polyurethane clear lacquer (47 891 ofHerberts GmbH)

The tests of humidity resistance (DIN 50017, condensed water testclimate, adhesion to the following layers) and the elasticity at aflexural test even at -20° C. (DIN 53152 or ISO 6860, adhesion to thesubstrate) demonstrate good results.

A comparative test was carried out in analogy with example 4, howeveromitting the CPO-polymer in the coating agent. This test demonstrated anessentially worse result of the adhesion test.

EXAMPLE 9

36.9% of an aqueous acrylate dispersion (Bayhydrol VPLS 2940, solidscontent 30%) are mixed under agitation with 7.4% demineralized water,1.3% of a commercial acrylate thickener, 0.15% of a commercialemulsifier and 0.25% of a commercial defoaming agent, whereafter themixture is mixed with 22.2% titanium dioxide. This mixture ishomogenously stirred and ground in a bead mill. 25.2% of a commercialCPO (20% in xylene) are added to this mixture and homogenized.

The thus obtained binder mixture is mixed with 6.6% of a commercialmixture of oligomeric HDI-condensation product having a NCO-content of22% and the obtained composition is homogenously mixed. The viscosityfor application is achieved by the addition of a low amount of water.

The thus obtained topcoat agent is sprayed onto a degreased plasticsubstrate in order to achieve a dry-film thickness of ca. 40 μm. Thefilm is aerated for 15 minutes and then dried for 15 minutes at 80° C.

The elasticity is tested by a flexural test (ISO 6860 or DIN 53152).

The adhesion to the substrate is good.

The adhesion to the substrate is clearly better than with a comparativetest being carried out without the CPO-solution.

We claim:
 1. An aqueous coating agent on the basis of one or morepolyols having ionic groups or groups convertible into ionic groups,which can contain pigments, fillers and/or optional conventional lacqueradjuvants and/or solvents, comprisingA) 10 to 40 wt.-% of one or morepolyols having a number-average molecular weight (Mn) of 500 to 200000,an OH-number of 15 to 300 and a content of ionic groups and/or groupsconvertible into ionic groups of 5 to 400 meq/100 g solid resin, whichare at least partly neutralized, B) 0.5 to 10 wt.-% of one or morechlorinated polyolefines having a chlorine content of 15 to 35 wt.-%, C)5 to 40 wt.-% of one or more aromatic solvents having a boiling rangefrom 100° to 160° C., D) 25 to 75 wt.-% of water, E) 0 to 30 wt.-% ofone or more further water dilutable binders which are free from groupsreactive with NCO,the percentages by weight of components A) to E)adding up to 100 wt.-% and F) one or more polyisocyanates having onaverage at least two free isocyanate groups per molecule, in such anamount that the ratio of the number of reactive isocyanate groups to theOH-groups of the polyols is 0.5:1 to 5:1,the coating agent being atwo-component system, one component containing the polyols and the othercomponent containing the polyisocyanates.
 2. An aqueous coating agentaccording to claim 1, characterized in that component A) containsanionic groups and/or substituents which are convertible into anionicgroups.
 3. An aqueous emulsion on the basis of one or more polyolshaving ionic groups or groups convertible into ionic groups, usable forthe preparation of the aqueous coating agents of claim 2, comprising:A)10 to 40 wt.-% of one or more polyols having a number average molecularweight (Mn) of 500 to 200,000, an OH-number of 15 to 300 and a contentof ionic groups and/or groups convertible into ionic groups of 5 to 400meq/100 g solid resin, which are at least partly neutralized, B) 0.5 to10 wt.-% of one of more chlorinated polyolefines having a chlorinecontent of 15 to 35 wt.-%, C) 5 to 40 wt.-% of one or more aromaticsolvents having a boiling range from 100° to 160° C., and D) 25-75 wt.-%of water.
 4. An aqueous emulsion according to claim 3, characterized inthat component A) contains anionic groups and/or groups convertible intoanionic groups.
 5. Coating agent or emulsion in accordance with claim 1or 3, characterized in that the polyol is based on radicallypolymerizable, olefinically unsaturated monomers having an OH-number of15-300 and an acid number of 2-250.
 6. Coating agent or emulsionaccording to claim 1 or 3, characterized in that the polyol is apolyurethane resin having an OH-number of 20-200 and an acid number of10-200.
 7. Coating agent or emulsion according to claim 1 or 3,characterized in that the polyol is a polyester having an OH-number of20-200 and an acid number of 20-150.
 8. Coating agent or emulsionaccording to claim 1 or 3, characterized in that it is essentially ortotally free from emulsifiers.